Table 1. Typical densities for Bay area rocks

Age is in millions of years; densities are in grams/cubic centimeters, M is magnetic


Rock type
Age
Range
Average

millions of years
grams/cubic centimeter
grams/cubic centimeter

Quaternary sediments (Qs)

Cenozoic volcanic rocksM
(Czv)
Tertiary sedimentary rocks
(Ts)
Cretaceous sedimentary rocks
(Ks)
Cretaceous and Jurassic
Franciscan Complex (KJf)
Mesozoic igneous rocks (Mzi)
(includes gabbroM)
Mesozoic metamorphic rocks (Mzm)
Mesozoic granitic rocks (Mzg)
Mesozoic serpentinite
(Mzsp)
0-2

0-65

2-65

65-140

65-210

65-250

65-250
65-250
65-250

1.7-2.2

2.2-2.7

2.2-2.6

2.6-2.7

2.6-2.8

2.7-3.0

2.6-2.8
2.6-2.8
2.2-2.8

2.0

2.5

2.4

2.65

2.67

2.8

2.7
2.67
2.4